This invention is concerned with the attachment of an electric cable to the motor of a submergible pump and is more particularly concerned with improved attachment devices or "potheads", as they are known in the art.
A state-of-the-art pothead employed commercially by the assignee of the present invention comprises a rigid metal shell (termed a "flange") containing a block of rubber through which the conductors of an electric cable extend, the ends of the conductors having terminals that engage corresponding terminals of the motor conductors. The rubber block is compressed between relatively rigid washers at opposite ends of the block. The washers and the rubber block are sealed to the inner surface of the flange, and the conductors are sealed within the washers and the block. The washer closest to the terminals is surrounded by a cylindrical gland packing, the packing being inserted in a recess formed by the external surface of the washer and the internal surface of the flange. A lead gasket is pressed into a small gap between a circumferential portion of the gland and an opposed portion of the flange. The gland projects from an end of the flange to engage the cylindrical wall of a lead-in bore of the motor head. An O-ring surrounds the gland and is compressed between an end of the flange and a portion of the motor head surrounding an end opening of the bore. The internal space in the shell beyond the other washer is filled with a strain relief material, such as epoxy resin.
In an earlier form of pothead employed by the assignee of the present invention, a cable-entry portion of the flange is filled with an elastomeric material and an adjacent cable-exit portion of the flange contains an aluminum block. The cable conductors extend through and are sealed into the elastomeric material and the aluminum block. A cylindrical gland surrounds an end portion of the aluminum block and fits between the block and the internal wall of the flange. An end of the gland and an end of the block are received between the end of the gland and a shoulder on the motor head.
Other forms of potheads are disclosed in Zehren U.S. Pat. No. 4,128,735 and in Arutunoff U.S. Pat. No. 2,283,117, both assigned to the assignee of the present invention.